1. Field of the Invention
This invention has relation to air pressure regulators and particularly to a type of air pressure regulator which can be preset to be capable of delivering air at any one of a number of preselected regulated pressures by stepping a regulator control through a number of different settings.
2. Description of the Prior Art
Compressed air is commonly used in many situations, for example in operating torque wrenches in manufacturing plants; spray painting; and in greasing, filling tires, removing tires from rims and operating other appliances at automobile service stations, to name but a few.
In each of these uses and in many other uses, it is desirable or necessary to have the air delivered at any one of several different carefully and accurately regulated pressures. For example, in an assembly plant, a major quality problem is loose or otherwise improperly torqued nuts and bolts. In such assembly operations, the proper torque for one particular nut and bolt assembly will not necessarily be the same as for another such assembly.
In certain air operated torque wrenches, the pressure of the incoming air determines the torque exerted. Before the present invention, in order to vary the pressure of the air supply and therefore the torque, it was necessary to manually turn an adjusting screw on an air pressure regulator to vary the tension in an adjusting spring until the desired pressure was obtained on an air gauge. This had to be done each time a different pressure was needed. This made the change of pressure very, very time consuming and made it virtually impossible to repeat the exact pressures time after time.
Another method of attempting to obtain the proper torquing requires use of an impact wrench connected to an air source at a single pressure. The operator then had to try to count the number of raps or impacts delivered by the wrench on a particular nut or bolt assembly and had to interrupt the operation of the wrench when the number corresponding to the desired torque was reached.
Another extremely expensive and cumbersome way to obtain different pressures which is currently in use is to hook the input conduits of three separate air pressure regulators to a single source of unregulated air pressure through a three-way valve, to set each regulator at a different pressure, and then to connect a different impact wrench to the outlet conduit of each of the regulators.
What was needed before the present invention was a single air pressure regulator which could be rapidly and substantially instantaneously adjusted to yield any one of a large number of different air pressures, and to do so in a manner that the air pressure delivered at a particular setting will be repeated accurately many times.
In a search of the prior art, the following patents were cited:
______________________________________ U.S. Pat. Nos. ______________________________________ 1,015,164 W. T. Fowden January 16, 1912 1,343,160 E. J. Schmidt June 8, 1920 2,735,669 E. E. Seiler February 21, 1956 ______________________________________
The Seiler patent discloses a calibrated cam means which replaces the adjustment screw in tensioning the spring operating on the diaphragm. In effect, this appears to be substantially the same mechanism as used in a standard regulator such as the Coilhose Pneumatics Fluid Power Products Air Line Regulator shown in Catalog Sheet PP-R479B, presented with this application; except that a cm 44 mounted on an axle 46 is turned by knob 56 in the Seiler patent whereas the adjustment of the adjusting spring 7 in the Coilhose Regulator is accomplished by rotating the adjusting screw assembly 1.
The patent to Fowden does not seem to be pertinent. It discloses merely an adjustment of a spool valve accomplished by the rotating of the spool to align it with more or less valve openings. A hand-wheel 15 rotates the spool valve and a finger 20 indicates the positioning of the valve spool inside of the valve.
The patent to Schmidt does not appear to be pertinent. It shows a pressure relief valve that is adjusted by adjusting the tension in a coiled spring by rotating a threaded sleeve having an indicator pointer thereon.
Applicants and those in privity with them are aware of no prior art which is closer than those discussed above and are aware of no prior art which anticipates the claims made herein.